is a 1901 queen victoria with a 'doubled" "9" a rare error coin or not? picture

1901 britsh queen victoria penny error coin any ideal of possible value? - the "doubling' is on the 9 it has a second part of another 9 --the loop part (front) of the 9 at the top ---its hard to see in the scan pic -- it is sort of lower than the top 9 like a "strike over" -- one 9 struck over top of another 9 with part of the lower 9 being slightly off center so it hung out a bit.